//翻转链表
//给你单链表的头节点 head ，请你反转链表，并返回反转后的链表。
//三指针逆置
struct ListNode* reverseList(struct ListNode* head) {
	struct ListNode* prev = NULL;
	struct ListNode* next = NULL;
	struct ListNode* cur = head;
	while (cur){
		next = cur->next;
		cur->next = prev;
		prev = cur;
		cur = next;
	}
	return prev;

}